In a known manner, a dispensing nozzle for a pressurized container includes an element for fixation to the container. This element may for example be a device that catches or nests on the bead retaining the valve cup on the container. Also in a known manner, the nozzle includes an ejection tube, which may be in a plane perpendicular to the axis of the emergent valve stem or may form a small angle with respect to such a plane; this ejection tube communicates with the emergent valve stem via a hole having the same axis as the emergent valve stem. When the user presses on the dispensing nozzle to actuate the valve, the emergent stem is introduced into the hole up to a projection where the coupling between the valve and the wall of the hole is tight, and then the wall of the hole transmits the thrust exerted by the user to the emergent stem, in such a way as to depress the stem and open the valve.
When a foaming product is dispensed, the use of nozzles of this type has several disadvantages. First, a small quantity of the product in the form of foam remains in the ejection tube and in the hole after the dispensing is finished; this product has a tendency to liquefy and run along the walls of the tube and hole to reach the emergent stem of the valve, with the risk that when the foam dries, it will stop up the ejection tube and the emergent valve stem. Second, when the dispensing stops, the expansion of the foaming product continues in the interior and at the outlet of the ejection tube; a spot of foam thus forms at the outlet of the ejection tube after the dispensing, and this spot has a tendency to soil the walls of the container.
Numerous proposals have been made to solve these various problems. In particular, it has been proposed that the emergent stem be displaced in a hole having a shape such that the coupling between the stem and the hole is tight in the operating position, and not tight in the position of repose. Under these conditions, the product that remains in the ejection tube and hole is capable of running into the space between the valve cup and the dispensing nozzle. The lack of tightness may be obtained with the aid of grooves hollowed out in the hole, as described in U.S. Pat. No. 4,901,891, or by arranging the device such that in the position of repose the emergent stem of the valve will have exited completely from the hole.
However, the lack of tightness of the coupling between the emergent valve stem and the hole does not enable solving the problem of eliminating the spot of foam that forms at the outlet of the ejection tube and at corresponding fins. Moreover, this solution is not very satisfactory for viscous products or products heavily laden with solid material, such as makeup bases, which have a high pigment content.
In order not to have to form external fins, the proposal has been made in French Patent Application No. 87-09536 to assure that the opening of the ejection tube outlet is plugged in the position of repose, with the opening being uncovered only during operation. Moreover, it has also been proposed, in U.S. Pat. 3,785,528, that a negative pressure be created in the space above the valve cup inside the dispensing nozzle, in such a way that the product remaining after the dispensation in the ejection tube is aspirated into this space. However, the devices proposed thus far do not enable precise control of the suction, and consequently do not allow reliable reaspiration of the product remaining in the ejection conduit.